[PATCH v5 3/5] crypto: drbg - add async seeding operation
From: Stephan Mueller <hidden>
Date: 2015-05-08 06:44:42
Also in:
lkml
Subsystem:
crypto api, the rest · Maintainers:
Herbert Xu, "David S. Miller", Linus Torvalds
The async seeding operation is triggered during initalization right after the first non-blocking seeding is completed. As required by the asynchronous operation of random.c, a callback function is provided that is triggered by random.c once entropy is available. That callback function performs the actual seeding of the DRBG. CC: Andreas Steffen <redacted> CC: Theodore Ts'o <tytso@mit.edu> CC: Sandy Harris <redacted> Signed-off-by: Stephan Mueller <redacted> --- crypto/drbg.c | 41 +++++++++++++++++++++++++++++++++++++++++ include/crypto/drbg.h | 1 + 2 files changed, 42 insertions(+)
diff --git a/crypto/drbg.c b/crypto/drbg.c
index 36dfece..693dac4 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c@@ -1056,6 +1056,40 @@ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, return ret; } +/* DRBG callback for obtaining data from the async Linux RNG */ +static void drbg_async_seed_cb(void *buf, ssize_t buflen, void *private) +{ + struct drbg_string data; + LIST_HEAD(seedlist); + struct drbg_state *drbg = (struct drbg_state *)private; + int ret = 0; + + if (buflen <= 0 || !buf) + return; + + drbg_string_fill(&data, buf, buflen); + list_add_tail(&data.list, &seedlist); + /* sanity check to verify that there is still a DRBG instance */ + if (!drbg) + return; + mutex_lock(&drbg->drbg_mutex); + /* sanity check to verify that the DRBG instance is valid */ + if (!drbg->V) { + mutex_unlock(&drbg->drbg_mutex); + return; + } + ret = __drbg_seed(drbg, &seedlist, true); + memzero_explicit(buf, buflen); + mutex_unlock(&drbg->drbg_mutex); +} + +/* Cancel any outstanding async operation and wait for their completion */ +static inline void drbg_async_work_cancel(struct random_work *work) +{ + get_blocking_random_bytes_cancel(work); + cancel_work_sync(&work->rw_work); +} + /* * Seeding or reseeding of the DRBG *
@@ -1125,6 +1159,12 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, if (!reseed) drbg->seed_buf_len = drbg->seed_buf_len / 3 * 2; + /* Invoke asynchronous seeding unless DRBG is in test mode. */ + if (!list_empty(&drbg->test_data.list)) + get_blocking_random_bytes_cb(NULL, &drbg->seed_work, + drbg->seed_buf, drbg->seed_buf_len, + drbg, drbg_async_seed_cb); + out: return ret; }
@@ -1487,6 +1527,7 @@ unlock: */ static int drbg_uninstantiate(struct drbg_state *drbg) { + drbg_async_work_cancel(&drbg->seed_work); if (drbg->d_ops) drbg->d_ops->crypto_fini(drbg); drbg_dealloc_state(drbg);
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index b052698..e4980a1 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h@@ -119,6 +119,7 @@ struct drbg_state { bool fips_primed; /* Continuous test primed? */ unsigned char *prev; /* FIPS 140-2 continuous test value */ #endif + struct random_work seed_work; /* asynchronous seeding support */ u8 *seed_buf; /* buffer holding the seed */ size_t seed_buf_len; const struct drbg_state_ops *d_ops;
--
2.1.0